This invention relates to colored contact lenses and methods of making colored contact lenses.
Colored contact lenses are often used for cosmetic purposes to change the apparent color of a wearer's irises. For example, a person with brown or blue eyes desiring to have green eyes may wear green colored contact lenses to change the apparent color of a wearer's iris to green.
Conventionally, coloring of contact lenses for cosmetic purposes is achieved by printing a colored pattern onto a lens substrate via a pad printing process. The pad printing process employs a generally flat steel plate also known as a cliché. A pattern (or depression) is etched into the cliché by a photo-etching process. In operation, ink placed in the pattern is transferred to the lens substrate by a printing pad. To achieve a colored lens of multiple colors, different colored inks are placed into three or fewer different patterns and serially transferred to the lens substrate by printing pads.
A disadvantage associated with conventional methods of coloring contact lens substrates is that such methods cannot achieve patterns of high detail or resolution. In other words, the printed pattern on the lens substrate does not have nearly the detail of a human iris. The inability to achieve patterns of high resolution also prevents use of more than three different patterns on a lens substrate. As such, an observer viewing the wearer's eyes from less than five feet away may determine that the wearer is wearing colored lenses.
Knapp U.S. Pat. No. 4,582,402 discloses a contact lens substrate having an intermittent opaque pattern thereon with portions left uncolored to allow the wearer's iris to show through. Knapp discloses that the pattern is not visible to the naked eye when viewed from a distance of at least five feet by an ordinary viewer (i.e., a person having normal 20/20 vision). However, the ordinary viewer viewing the wearer's eyes from a closer distance might determine that the pattern is not a naturally occurring pattern. In other words, the ordinary viewer might correctly determine that the wearer is wearing colored contact lenses.
Jahnke U.S. Pat. No. 5,414,477 and O'Campo U.S. Pat. No. 5,963,705, like the Knapp patent, disclose contact lenses having opaque intermittent elements and noncolored regions through which significant portions of the wearer's iris structure are visible. These patents disclose making the intermittent elements of a single contact lens having up to three different color elements. However, because an actual human iris typically is an intricate looking structure having hundreds or thousands of different colors, contact lenses of these prior art patents allow the structure of the iris to show through the uncolored portions. One disadvantage of allowing significant portions of the wearer's iris to show through is that the visible portions of the wearer's iris combined with the visible portions of the intermittent pattern sometimes results in an unnatural looking iris. In particular, if the wearer's iris is dark brown and the colored elements of the contact lens pattern is light, the combination results in a pronounced, hyper-contrast which does not look natural.